With the recent development of biometric technology, provided are various types of devices for personal identification by recognizing the physical characteristics of a body part of a person by capturing, for example, the fingerprints of limbs, the retina of an eye, the face, the blood vessels, etc. of a person.
Especially, since the blood vessels of a palm or a finger, and palm prints provide a relatively large amount of personal characteristic data, they are appropriate for personal identification with reliability. Furthermore, the pattern of blood vessels (vein) is not changed throughout one's lifetime after it is determined in the womb, that is, unique throughout the world, which is appropriate for personal identification.
As a concrete method of capturing a vein image, an illumination device emits near-infrared light to the palm, the near-infrared light reflected by the palm is captured by a camera provided with an image sensor (patent documents 1 and 2). Since the hemoglobin in the red blood cells absorbs the near-infrared light, the quantity of the reflected near-infrared light from the vein parts decreases when the near-infrared light is emitted to the palm. Therefore, the camera may shoot the position of the vein on the palm based on the strength level of the near-infrared light.
There may be restrictions on the installation of a vein image capture device designed as a unitary construction of an illumination device and a camera. For example, when the vein image capture device is to be installed on the door of an apartment, the vein image capture device requests the thickness for the device to be embedded in the door.    Patent Document 1: Japanese Laid-open Patent Publication No. 2007-249615    Patent Document 2: Japanese Laid-open Patent Publication No. 2007-30569